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Response surface methodology was applied to investigate the optimum degradation conditions of paracetamol using Ag/BiVO4 photocatalysts under the visible light irradiation. Experimental results show that the optimum degradation conditions were: catalyst dosage quantity was 80 mg, Ag-catalyst loading was 5%, and the initial pH value of the solution was 6, respectively. Under this condition, the degradation efficiency of paracetamol was 77.9% within 5 h under the visible light irradiation.

An efficient method for the degradation of ibuprofen as an aqueous contaminant was developed under visible-light irradiation with as-prepared bismuth vanadate (BiVO 4 ) catalysts. The metal-loaded catalysts Cu–BiVO 4 and Ag–BiVO 4 were synthesized using a hydrothermal process and then a wet-impregnation method. All of the materials were fully characterized by X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and BET surface area. The results indicated that all of the prepared samples had monoclinic scheelite structures. In the metal-loaded catalysts, silver existed as a mixture of Ag and Ag 2 O on the surface of the catalysts. However, copper existed as Cu 2 O and CuO. Additionally, the band gap values of BiVO 4 , Ag–BiVO 4 , and Cu–BiVO 4 were 2.38, 2.31, and 2.30 eV, respectively. Compared to the BiVO 4 catalyst, the metal-loaded BiVO 4 catalysts showed superior photocatalytic properties for the degradation of ibuprofen.

Pd/graphene catalysts were prepared in situ from graphite oxide and palladium salts by the hydrogen-reduction method and were then used for the construction of Pd/graphene gas-diffusion electrodes (GDE). The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential pulse voltammetry (DPV) techniques. In the Pd/graphene catalysts, Pd particles, with an average size of 3.6 nm and an amorphous structure, were highly dispersed in the graphene. The Pd/graphene catalysts accelerated the two-electron reduction of O2 to H2O2 by feeding air, which favors the production of hydroxyl radicals (HO*). In the electrolytic system, HO* was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The dechlorination degree of 4-chlorophenol reached approximately 90.5% after 80 min, and the removal efficiency and the average removal efficiency of 4-chlorophenol, in terms of total organic carbon (TOC) after 120 min, reached approximately 93.3% and 85.1%, respectively. Furthermore, based on the analysis of electrolysis intermediates by high performance liquid chromatography (HPLC) and ion chromatography (IC), a reaction scheme was proposed for the Pd/grapheme GDE catalytic degradation of 4-chlorophenol.

The Pd-Fe/graphene multi-functional catalytic cathode was prepared by UV-assisted photocatalytic reduction. The catalytic cathode and a Ti/IrO₂/RuO₂ anode consisting of both three-electrode system (two cathodes) and two-electrode system (one cathode) were designed for the degradation of 4-chlorophenol in aid of olectrochemical reducing and oxidizing processes. The concentrations of the intermediates and products were monitored by high performance liquid chromatography (HPLC), total organic carbon (TOC), and ion chromatography (IC). The theoretical toxicity was calculated according to the formula. The actual toxicity of the solution during the degradation process was detected using the luminescent bacteria. The comparison of the actual toxicity and theoretical toxicity was performed to analyze the trend of the two systems. The results showed that the toxicity of the solution in anode compartment first increased and then decreased, but the toxicity in cathode compartment decreased during the whole degradation for both systems. This trend could be attributed to the intermediate formed, benzoquinone. Through the analysis of correlation, the correlation coefficient was 1 of the theoretical toxicity and actual toxicity at the level of P = 0.01, which indicated the result of toxicity was reliable. The toxicity of three-electrode system was lower than that of two-electrode system after 120 mm. The three-electrode system was considered to be better than the two-electrode system. Therefore, the detection of actual toxicity in electrochemical reducing and oxidizing process for the degradation of chlorophenols in the actual industry has wide application prospect.

In a diaphragm electrolyze system with a Ti/RuO2/IrO2 anode and the Pd/MWNTs gas diffusion cathode, the degradation of 2-chlorophenol was fully studied by the electrochemical reduction and the simultaneous oxidation of the cathode and anode. The results indicated that the Cl- removal reached 90.5% after 80 min electrolysis with H2 feeding. After 120 min electrolysis, the removal of 2-chlorophenol in the anodic and cathode compartments were 88.8% and 98.5%, respectively. Additionally, the TOC removal reached 75% and 85.6% in the anodic and cathodic compartment respectively after 140 min. By the UV scanner analysis of the electrolyte, the 4-chlorophenol and benzoquinone were oxidized by the oxides formed on the cathode, while the benzoquinone was found accumulated in the anodic compartment. Based on the analysis of electrolysis intermediates using high performance liquid chromatography (HPLC) and ion chromatography (IC), the electrolysis degradation of 2-chlorophenol was proposed containing the intermediates, such as phenol, hydroquinone, benzoquinone, maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid, acetic acid and formic acid.

Two RuII/ReI dimers, [Ru(dmb)2(L1)Re(CO)3Cl] (1) and [Ru(dmb)2(L2)Re(CO)3Cl] (2), were synthesized and characterized, and their electrochemical and spectroscopic properties together with their photocatalytic CO2 reduction activities were evaluated (dmb = 4,4′-dimethyl-2,2′-bipyridine; L1 = 1,2-bis(4′-methyl-2,2′-bipyridyl-4-yl)ethane; L2 = 1,2-bis(4′-methyl-2,2′-bipyridyl-4-yl)ethene). The structures of 1 and 2 are identical except for the difference in the conjugation content of bridging ligands (–CH2–CH2– for 1 and –CH CH– for 2). Density functional theory (DFT) methods were employed to model the ground-state electronic transition and electrochemical properties of both catalysts. Electronic transitions were identified using UV–Vis spectroscopic techniques, aided by time-dependent density functional theory (TD-DFT) methods. The redox properties of two complexes under N2 and CO2 pressure have been studied by means of cyclic voltammetric measurements. When the cyclic voltammetry was performed in the presence of CO2, a substantial current enhancement was observed for the reduction wave of 1 and 2. Additionally, significant higher turnover numbers of CO formation in the photocatalytic CO2 reduction are observed for 1 than that for 2. Although complex 2 exhibited longer wavelength absorption, its photocatalytic activation for the CO2 reduction was lower than that of 1, due to the effect of conjugated linkage on the reduction potential and low emission quantum yield.

In a diaphragm electrolyze system with a Ti/RuO2/IrO2 anode and the Pd/MWNTs gas diffusion cathode, the degradation of 4-chlorophenol was fully studied by the electrochemical reduction and the simultaneous oxidation of the cathode and anode. The results indicated that the optimization electrolyte concentration is 0.08 mol/L. The Cl- removal reached 94.8% after 80 min electrolysis with H2 feeding. After 120 min electrolysis, the removal of 4-chlorophenol in the anodic and cathode compartments were 98.5% and 90.6%, respectively. Additionally, the TOC removal reached 65% and 70% in the anodic and cathodic compartment respectively after 140 min. By the UV scanner analysis of the electrolyte, the 4-chlorophenol and benzoquinone were oxidized by the oxides formed on the cathode, while the benzoquinone was found accumulated in the anodic compartment.

A novel tripodal ligand, tris[(4'-methyl-2,2'-bipyridin-4-yl)methyl]carbinol (tb-carbinol) and its homonuclear and heteronuclear Ru(II)-Re(I) complexes have been synthesized and characterized by NMR spectroscopy, elemental analysis, and mass spectroscopy. The spectroscopic, electrochemical and photocatalytic properties of the Ru(II)-Re(I) complexes have been investigated. In these supramolecular complexes with tb-carbinol as a bridging ligand, the intramolecular interaction among the terminal metal centers is very weak. In the cases of Ru(II) and Re(I) heteronuclear systems, when the Re(I) moieties are excited, the emission from the Re(I) moiety is efficiently quenched and the intensity of the emission from the Ru(II) moiety increases. The rate constant of energy transfer from Re(I) moieties to Ru(II) unit in RuRe(2) is 1.7 x 10(8) s(-1). From the point of view of the free energy change, the intramolecular electron transfer from the Ru(II) moiety to the Re(I) moiety could proceed smoothly in the ground state. Both of Ru(2)Re and RuRe(2) show excellent photocatalytic activities to the CO(2) reduction. RuRe(2) exhibits a turnover number of 190 for CO formation compared with 89 from the model complexes system after 16 h of irradiation (TN(CO) calculated based on Ru(II) moiety concentration). Ru(2)Re shows a higher turnover number than the model complexes system, 110 compared with 55 from the model system (TN(CO) calculated based on Re(I) moiety concentration). The bridging ligand of Ru(II)-Re(I) heteronuclear tripodal systems, tb-carbinol, plays an important role in converting radiant energy to chemical energy in the form of CO from CO(2). Enhancement of the photocatalytic response to light in the visible region has been achieved by fabricating supramolecular systems featuring covalently linked Ru(II) and Re(I) moieties.

Cyclometalated platinum(II) complex, [ClPt(C^N^NPhMe)] ( 1 ) (HC^N^NPhMe = 4-( p -tolyl)-6-phenyl-2,2′-bipyridine) was found to be an efficient photosensitizer for photocatalytic hydrogen evolution from water, 98 turnovers of hydrogen were obtained after 10 h irradiation of solution containing MV 2+ (4,4′-dimethyl-2,2′-bipyridinium), triethanolamine (TEOA), photosensitizer and colloidal Pt, which is far effective than that of platinum(II) terpyridyl complex [ClPt(N^N^NPhMe)]ClO 4 ( 2 ) (N^N^NPhMe = 4′-( p -tolyl)-2,2′:6′,2″-terpyridine). Net photocatalytic reduction of MV 2+ by the complexes in the presence of TEOA in CH 3 CN/H 2 O solvents were observed and compared upon irradiation ( λ > 400 nm).

A Pd-Fe/graphene multifunctional catalytic cathode was prepared to build a diaphragm electrolysis system with a Ti/IrO2/RuO2 anode and an organicterylene filter cloth. The degradation of organic wastewater containing 4-chlorophenol by combination of cathodic hydrogenation dechlorination and oxidation of anode and cathode was investigated. The degradation process was monitored and characterized in aid of TOC analysis, UV-Vis spectra, high performance liquid chromatogram, and ion chromatogram. The results showed that the degradation efficiencies of 4-chlorophenol in the present system with Pd-Fe/graphene catalytic cathode were 98.1% (in cathodic chamber), 95.1% (in anodic chamber) under the optimal conditions, which were higher than those of the Pd/graphene catalytic cathode system (93.3% in cathodic chamber, 91.4% in anodic chamber). The chloride ion removal rate was more than 95% in the Pd-Fe/graphene catalytic cathode system, which suggested that the bimetallic catalyst had stronger hydrogenation capacity. 4-chlorophenol could be completely removed within 120 min under the synergetic effect of anodic-cathodic electrochemical degradation. In the cathodic chamber, 4-chlorophenol was initially reduced to form phenol under electrocatalytic hydrolysis. With further oxidation in both cathodic and anodic chambers, phenol was converted into hydroquinone and benzoquinone, then low molecular weight organic acids, and finally CO2 and H2O. Moreover, a reaction pathway involving all these intermediates was proposed.

Palladium-graphene nanocomposites catalysts for the conversion of CO2 to formic acid were prepared by means of sodium borohydride reduction of K2PdCl4 in a graphite oxide suspension, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV) technologies. The characterization results showed that graphene with a d-spacing of 3.82 Å was fabricated, and palladium nanoparticles with an average size of 3.8 nm were highly dispersed in the graphene sheets with amorphous structure. The cyclic voltammogram analyses indicated palladium-graphene nanocomposites catalysts posed high catalytic activity for the CO2 reduction and the rate-determining step was the CO2 diffusion process from bulk solution to electrode surface. Then the electrocatalytic reduction of CO2 was investigated in a diaphragm electrolysis device, using Pd/graphene gas-diffusion electrode as a cathode and a Ti/RuO2 net anode. The reduction process was optimized by the application of factorial design 2(3) (voltage, reaction time and electrolyte concentration) and response surface methodology (RSM). Optimum conditions for the production of formic acid were given as following: voltage: 5.1 V, reaction time: 50.4 min and electrolyte concentration: 0.5 mol L(-1). The yield of formic acid formation was 3157.7 mg L(-1) and Faraday efficiency was 86.9% under the optimum operation condition.

An efficient method for the degradation of ibuprofen as an aqueous contaminant was developed under visible-light irradiation with as-prepared bismuth vanadate (BiVO4) catalysts. The metal-loaded catalysts Cu-BiVO4 and Ag-BiVO4 were synthesized using a hydrothermal process and then a wet-impregnation method. All of the materials were fully characterized by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and BET surface area. The results indicated that all of the prepared samples had monoclinic scheelite structures. In the metal-loaded catalysts, silver existed as a mixture of Ag and Ag2O on the surface of the catalysts. However, copper existed as Cu2O and CuO. Additionally, the band gap values of BiVO4, Ag-BiVO4, and Cu-BiVO4 were 2.38, 2.31, and 2.30eV, respectively. Compared to the BiVO4 catalyst, the metal-loaded BiVO4 catalysts showed superior photocatalytic properties for the degradation of ibuprofen.

A new bridging ligand, 1,3-bis(4′-methyl-2,2′-bipyridin-4-yl)propan-2-one (L) and its mono- and dinuclear Ru(II) complexes have been synthesized and characterized. The carbonyl group in L keeps its character and does not affect the Ru(II) moieties. In addition, the two Ru(II) terminuses of the dinuclear complex have no interaction through the bridging linkage.

A novel tripodal ligand, tris[(4'-methyl-2,2'-bipyridyl-4-yl)methyl]carbinol (L), has been synthesized. The spectroscopic, electrochemical, and photocatalytic properties of the new trinuclear complexes (Ru(2)Re and RuRe(2)) linked by the tripodal bridging ligand L are then investigated. In addition, 2-fold-improved photocatalytic activities were obtained in the case of these trinuclear complexes compared to the mixtures of the appropriate monometallic model complexes in the reduction of CO(2) under visible irradiation.

Nitric acid in various volume fraction (8%, 15%, 20%, and 68%) was used on the multi-wall carbon nanotubes (MWNTs) pre-treatment and then the formaldehyde reduction method was utilized for the preparation the Pd/MWNTs catalysts which were fully characterized by Boehm titration method, X-ray diffraction (XRD), infrared spectroscopy, scanning electron microscopy (SEM), and cyclic voltammetry(CV) techniques. The electrochemical degradation of 4-chlorophenol was investigated in a diaphragm electrolysis system using the Pd/MWNTs gas-diffusion cathode. The results indicated that the active organic function groups increased on the surface of the carbon nanotube pre-treated by using 68% nitric acid. Pd particles with an average size of 9.2 nm were highly dispersed in the carbon nanotube with an amorphous structure. Additionally, the Pd/MWNTs catalyst in Pd/MWNTs gas-diffusion electrode system accelerated the two-electron reduction of O2 to hydrogen peroxide (H2O2) when feeding air. The Pd/MWNTs gas-diffusion cathode can not only reductively dechlorinate 4-chlorophenols by feeding hydrogen gas, but also accelerate the two-electron reduction of O2 to H2O2 by feeding air. Therefore, the removal efficiency and the average removal efficiency of 4-chlorophenol in terms of total organic carbon (TOC) reached about 86.9% and 71.6% after 140 min electrolysis, respectively.

Two novel facial-capping tris-naphthyridyl compounds, 2-chloro-5-methyl-7-((2,4-dimethyl-1,8-naphthyridin-7(1H)-ylidene)(2,4-dimethyl-1,8-naphthyridin-7-yl))methyl-1,8-naphthyridine (L(1)) and 2-chloro-7-((2-methyl-1,8-naphthyridin-7(1H)-ylidene)(2-methyl-1,8-naphthyridin-7-yl))methyl-1,8-naphthyridine (L(2)), as well as their Cu(i) and Pb(ii) complexes, [CuL(a)(PPh(3))]BF(4) (1) (PPh(3) = triphenylphosphine, L(a) = bis(2,4-dimethyl-1,8-naphthyridin-7-yl)(2-chloro-5-methyl-1,8-naphthyridin-7-yl)methane), [CuL(b)(PPh(3))]BF(4) (2) (L(b) = bis(2-methyl-1,8-naphthyridin-7-yl)(2-chloro-1,8-naphthyridin-7-yl)methane), [Pb(OL(a))(NO(3))(2)] (3) (OL(a) = bis(2,4-dimethyl-1,8-naphthyridin-7-yl)(2-chloro-5-methyl-1,8-naphthyridin-7-yl)methanol) and [Pb(L(b))(2)][Pb(CH(3)OH)(NO(3))(4)] (4), have been synthesized and characterized by X-ray diffraction analysis, MS, NMR and elemental analysis. The structural investigations revealed that the transfer of the H-atom at the central carbon to an adjacent naphthyridine-N atom affords L(1) and L(2) possessing large conjugated architectures, and the central carbon atoms adopt the sp(2) hybridized bonding mode. The reversible hydrogen transfer and a geometric configuration conversion from sp(2) to sp(3) of the central carbon atom were observed when Pb(II) and Cu(I) were coordinated to L(1) or L(2). The molecular energy changes accompanying the hydrogen migration and titration of H(+) to different receptor-N at L(1) were calculated by density functional theory (DFT) at the SCRF-B3LYP/6-311++G(d,p) level in a CH(2)Cl(2) solution, and the observed lowest-energy absorption and emission for L(1) and L(2) can be tentatively assigned to an intramolecular charge transfer (ICT) transition in nature.

Using a self-made Pd/C gas-diffusion electrode as the cathode and a Ti/IrO2/RuO2 anode, the degradation of 4-chlorophenol has been investigated in an undivided electrolysis device by the electrochemical oxidation processes. The result indicated that the neutral aqueous solutions can accelerate 4-chlorophenol degradation during electrolysis. The removal efficiency of 4-chlorophenol and COD reached about 89.6% and 62.0% after 120 min electrolysis, respectively. It suggested that most of 4-chlorophenol was oxidised to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the biodegradation ability of the solution was increased significantly during the electrolysis. The degradation of 4-chlorophenol was attributed to the cooperative oxidation processes including electrochemical oxidation at the anode and H2O2 and hydroxyl radical (HO·) produced by the reduction of oxygen at the cathode. Finally, main aromatic intermediates (e.g., hydroquinone and benzoquinone) and main aliphatic carboxylic intermediates (e.g., oxalic, malonic, maleic, succinic, fumaric, and dodecanoic acids) were identified by GC-MS. Moreover, a reaction scheme involving all these intermediates was proposed.

Using a self-made Pd/C gas-diffusion electrode as the cathode and Ti/IrO2/RuO2 as the anode, the degradation of phenol was investigated in an undivided electrolysis device by the electrochemical oxidation process. Hydroxyl radical (*OH) was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The result indicated that the Pd/C catalyst in Pd/C gas-diffusion electrode system accelerated the two-electron reduction of O2 to H2O2 when feeding air, which is in favor of producing *OH. After 120 min electrolysis in Pd/C gas-diffusion electrode system, the steady concentration of H2O2 was 7.5 mg/L. The removal efficiency of phenol and COD reached about 97.2% and 50% after 120 min electrolysis, respectively, which suggested that most of phenol were oxidized to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the ratio of BOD5/COD of the solutions was 9.1 times larger than the initial ones. Hence the electrochemical oxidation can enhance the biodegradation character of the phenol solution. The degradation of phenol was supposed to be cooperative oxidation by direct and/or indirect electrochemical oxidation at the anode and H2O2, *OH produced by oxygen reduction at the cathode. UV-Vis and GC-MS identified catechol, hydroquinone, and benzoquinone as the main aromatic intermediates, and adipic, maleic, fumaric, succinic, malonic, and oxalic acids as the main aliphatic carboxylic intermediates. A reaction scheme involving all these intermediates was proposed.

The photocatalytic activity for CO(2) reduction and optical and electrochemical properties of two Ru(II)-Re(I) binuclear complexes [Ru(dmb)(2)LRe(CO)(3)Cl](2+) (Ru-Re and Ru=Re, dmb = 4,4'-dimethyl-2,2'-bipyridine) with 1,2-bis(4'-methyl-2,2'-bipyridyl-4-yl)ethane and 1,2-bis(4'-methyl-2,2'-bipyridyl-4-yl)ethene as bridging ligands have been investigated. The conjugation content of the bridging ligands plays an important role in the photocatalytic behavior: a saturated linkage exhibited more efficient than the conjugated.

A new ligand N, N-bis[(diphenylphosphino)methyl]-2-pyridinylamine (L) and its luminescent dinuclear copper(I) complex [CuBrL]1 (1) were synthesized and characterized by mass spectrometry, elemental analysis, NMR and electronic spectroscopies. The structure of complex 1 was determined by X-ray crystal analysis to be a dinuclear complex with a pseudo-tetrahedral geometry. The complex 1 crystallizes in a triclinic space group P-1 and has two copper(I ) centers bridged by two halogen ligands to form the dinuclear structure with a four-membered Cu2 Br2 ring. The Cu-Cu distance in complex 1 is 0.306 0 nm which is longer than a sum of Van der Waals radius of two copper( I ) atoms. Therefore there is no substantial interaction between the two copper(I) centers in complex 1. DFT calculations indicate that the electron density of HOMO is distributed mainly over the copper, bromine and phosphorus atoms, while that of LUMO is localized on the ligand. Our work shows that there are two mechanisms to form the the lowest excited state of complex 1, i.e. the metal-to-ligand charge transfer (MLCT) and halogen-to-ligand charge transfer (XLCT).

Using a self-made Pd/C gas-diffusion electrode as the cathode and a Ti/IrO 2 /RuO 2 anode, the degradation of diethyl phthalate (DEP) has been investigated in an undivided electrolysis device by electrochemical oxidation processes. Hydroxyl radical (HO ) was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The result indicated that the Pd/C catalyst in Pd/C gas-diffusion electrode system accelerated the two-electron reduction of fed O 2 to H 2 O 2 , which is in favor of producing HO . Additionally, the percentage removal of DEP and COD reached about 80.9 and 40.2% after 9 h electrolysis, respectively. It suggested that most of DEP were oxidized to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the ratio of BOD 5 /COD of resulted solutions was three times larger than the initial ones. Hence, the electrochemical oxidation enhanced the biodegradation character of the DEP solution. Finally, main aromatic intermediates (e.g., monoethyl phthalate (MEP) and phthalic acid (PA)) and main aliphatic carboxylic intermediates (e.g., formic, mesoxalic, oxalic, malonic, succinic, maleic, dodecanoic, and hexadecanoic acids) were identified by GC–MS. Moreover, a reaction scheme involving all these intermediates was proposed.